Sources: Rahm dials unions for Priorities USA contributions (UPDATED)

11/1/12 3:41 PM EDT

Chicago Mayor Rahm Emanuel has been calling labor unions over the past week and making a forceful case that they contribute six-figures and up to President Barack Obama’s super PAC, multiple sources tell POLITICO.

Some of the unions contacted have already budgeted their political activity for the year and are considering whether to take out loans to help the late push by Priorities USA.

One of the labor groups Emanuel contacted was the Laborers, a construction union.

They declined to say whether they'd make a contribution but signaled in a statement that they were considering the possibility.

"LIUNA is utilizing the power of our membership and our financial resources in an historic get out the vote effort to reelect President Obama and Vice President Biden," said Richard Greer, a spokesman for the Laborers. "Despite the avalanche of corporate cash flowing to candidates our members oppose, the proud men and women of LIUNA continue to express an unprecedented level of support for the president’s reelection and are utilizing every tool available to reach out to hundreds of thousands of co-workers, friends and neighbors in states across the country."

Ed Grebow, CEO of the union-owned Amalgamated Bank, confirmed in an interview that in recent days he had approved a number of sizable loans to unions.

“We have had a very busy election season,” said Grebow. “We’ve done more loans to PACs than in recent years.”

Grebow cited confidentiality laws when asked what specific unions he lent to, but said he had just signed off on one earlier in the day. He also allowed that the Laborers are “a very important client.”

Amalgamated is one of the few banks in the country that will make loans to PACs. They typically range from the low six-figures to a few million dollars.

The Democratic superPAC, run by former Obama aides, has lagged behind the major GOP third-party groups but is credited with doing damage to Romney with a tough Ohio ad. Priorities had only about $10 million as of mid-October and has spent heavily since then on TV ads and is urgently trying to raise cash to bolster its ad campaign in the race’s final days.

Emanuel, sources familiar with the calls say, has been asking for at least six-figures and in at least one case requested a union contribute $1 million.

The famously hard-charging mayor and former White House chief of staff has shown emotion on the calls but has so far received mixed results. While some unions are weighing loans, others are begging off entirely.

“We have our own races, and five days out is [a] little late,” says one top union official in Washington.

Obama and labor have had a up-and-down relationship since his primary bid against Hillary Clinton, when many unions backed Clinton. The president never made the Employee Free Choice Act, labor’s central organizing goal, a legislative priority. And some unions look at Emaunel warily because of his pragmatic approach in the White House and most recent confrontation with Chicago teachers. But unions have appreciated Obama’s labor-friendly appointees to the NRLB and rallied to the president in the face of Romney’s tough talk about “union stooges.”